Most memory module cards of a computer are Double Data Rate Synchronous Dynamic Random Access Memories (DDR SDRAM), which is an SDRAM with double data transmission rates. The data transmission rate is twice as fast as system time-pulse, different than SDR (Single Data Rate) which merely read/write once in a single period. The “Double” in DDR means that data is read/write twice in a single period. When the core clock rate remains the same, the transmission efficiency is double that of the SDR SDRAM.
Since the transmitting speed of memory module card is getting faster and faster, the demand for dissipating heat is getting bigger and bigger. However, the intervals between the memory module cards are unavoidably limited by the memory module card connectors mounted in a computer host, and are hard to change, which results in the worse efficiency of the heat dissipation of memory module card.